A patient is to be given 12 units of insulin. If 1 ml of insulin solution contains 40 units, how much insulin is to be given in ml?

Appeared in: RRB Staff Nurse Jaipur-6th June 2018

Explanation

The standard formula for medication dosage calculation is: Amount to Administer = (Dose Ordered / Dose on Hand) × Volume.
The dose ordered is 12 units, and the dose on hand is 40 units in 1 ml of solution.
Plugging the values into the formula: (12 units / 40 units/ml) × 1 ml.
The calculation results in 0.3 ml, which is the precise volume needed to deliver the prescribed 12 units of insulin.

Option A: This volume would deliver 20 units of insulin (0.5 ml × 40 units/ml), which is a significant overdose and could cause severe hypoglycemia.
Option B: This volume would deliver 16 units of insulin (0.4 ml × 40 units/ml), which is an overdose and poses a risk of hypoglycemia.
Option D: This volume would deliver 8 units of insulin (0.2 ml × 40 units/ml), which is an underdose and would be ineffective in managing the patient's blood glucose, leading to hyperglycemia.

Visual 1: Diagram - An illustration of a U-40 insulin syringe, highlighting the markings to show how 0.3 ml is accurately measured.
Visual 2: Infographic - The drug calculation formula (Dose Ordered / Dose on Hand) x Volume, with the values from the question (12 units, 40 units, 1 ml) clearly labeled.

Clinical Relevance

Nursing practice connection: Use the key finding related to Insulin Dosage Calculation to guide bedside assessment, documentation, and the next nursing action.
Insulin is a high-alert medication; calculation errors can lead to severe hypoglycemia (from an overdose) or hyperglycemia (from an underdose), both of which are life-threatening emergencies.
It is critical to use an insulin syringe that matches the insulin concentration. In this case, a U-40 syringe must be used for U-40 insulin to prevent dosing errors. Using a more common U-100 syringe would lead to a dangerous miscalculation.
In many clinical settings in India, U-40 insulin is still common. Nurses must be vigilant in checking the vial concentration before every administration.

How to Approach the Question

Step 1: Identify the key values provided in the question: Dose Ordered (D), Dose on Hand (H), and the Volume (V) the dose is available in.
Step 2: Recall the universal formula for drug calculation: Amount to Administer = (D / H) x V.
Step 3: Substitute the identified values into the formula: Amount = (12 units / 40 units/ml) x 1 ml.
Step 4: Perform the mathematical calculation: 12 divided by 40 equals 0.3.
Step 5: Compare the calculated result (0.3 ml) with the given options to select the correct one.

Concept Tested & Keywords

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Practise the full RRB Staff Nurse Jaipur-6th June 2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.